The evolved universal terrestrial radio access network (E-UTRAN) of the third generation mobile communication long term evolution (LTE) is composed of the enhanced base station (eNB), which supports the hybrid automatic repeat request (HARQ) function and is used for improving the reliability of successful transmission. The user equipment (UE) has an HARQ entity in downlink and uplink respectively, and the HARQ entity supports the plurality of HARQ processes and follows parallel stop-and-wait protocol. The HARQ information mainly includes: HARQ process information, new data indicator (NDI) information and redundancy version information. The uplink supports the synchronous HARQ, implying that the HARQ process identifier can be obtained according to the subframe number. The downlink supports the asynchronous HARQ, implying that the HARQ process identifier is indicated according to the downlink control information (DCI). The first transmission of the HARQ and the retransmission of the HARQ use the same HARQ process.
The E-UTRAN supports the dynamic scheduling. The dynamic scheduling refers to that E-UTRAN can dynamically allocate the resource to the UE through the cell radio network temporary identifier (C-RNTI) on the physical downlink control channel (PDCCH) at each transmit time interval (TTI) corresponding to one subframe, for example, the physical resource block (PRB) and modulation and coding scheme (MCS), etc. The PDCCH mainly carries the resource allocation information, mainly including the information such as the resource block (RB) allocation information, the MCS, the HARQ information, etc. In uplink, the UE generates data packets according to the information and sends the data packets to the base station through the physical uplink shared channel (PUSCH). The E-UTRAN sends for the data packets the acknowledgement response message (ACK)/non-acknowledgement response message (NACK) of the feedback hybrid automatic repeat request through the physical HARQ indicator channel (PHICH). In the downlink, the UE receives in the physical downlink shared channel (PDSCH) the data packets sent by the base station according to the information. The UE sends the ACK/NACK of the feedback hybrid automatic repeat request for the data packets through the PUSCH or the physical uplink control channel (PUCCH).
The E-UTRAN also supports the semi-persistent scheduling. The semi-persistent scheduling is suitable for the service of which the data packet is minor and the transmission time interval is relatively fixed, and the purpose is to reduce the signaling expense. The semi-persistent scheduling refers to that: the E-UTRAN can semi-persistently allocate the resource through the special C-RNTI on the PDCCH to the UE, including the PRB and the MCS, etc. The resource can only be used for the first transmission of the HARQ, and the resource can be reused periodically, and the typical period is 20 ms. When needed, the retransmission information is indicated with the explicit signaling through the PDCCH, that is, the retransmission of the HARQ retransmission uses the dynamic scheduling. The semi-persistent scheduling is initially configured by the radio resource control (RRC) signaling, for example, allocating the period of the semi-persistent scheduling. Wherein, the special C-RNTI and C-RNTI used by the dynamic scheduling are different.
In the uplink, the E-UTRAN also supports the TTI bundling. The TTI bundling is suitable for the users of the cell border, and the purpose is to improve the reliability of the successful transmission. The UTRAN allocates the resource for the first transmission and the retransmission of the HARQ sent by the UE, including PRB and MCS, etc. Once the TTI bundling is configured, that is, one group of subframes are configured, the UE utilizes the same resource to send the first transmission and the retransmission of the HARQ in this one group of subframe, meaning that the C-RNTI used to allocate the resource each time is not only used for the first transmission of the HARQ but also used for the retransmission of the HARQ. No matter the uplink transmission in the bundling is successful or not, the continuous subframes of the UE in the bundling are in one group of TTIs, and the UE occupies an identical HARQ process to transmit the uplink data, including the first transmission and a plurality of non-adaptive retransmissions, and the UD does not need to judge whether the last transmission is successful when retransmitting. The moment of the feedback for the uplink data is based on the last subframe of this group of the TTIs.
At present, the third generation partnership projects (3GPP) introduces the long term evolution advance (LTE-A) standard. Wherein, the wireless relay technology is one of the technologies in the LTE-A, which aims at expanding the coverage area of the cell, reducing the corner area in the communication, balancing the load, transferring the service of the hot spot area, and saving the transmitting power of the UE.
FIG. 1 is a structure diagram of the network utilizing the wireless relay technical in the related art. As shown in FIG. 1, some new relay nodes (RN) are added between the original base station (Donor-eNB) and the UE, and these newly-added RNs and Donor-eNB are connected wirelessly, and there is no wired connection with the transmission network. Wherein, the wireless link between the Donor-eNB and the RN is called a backhaul link, and also can be called the Un interface; and the wireless link between the RN and the UE is called an access link. The downlink data reaches the Donor-eNB firstly, and then the data are transmitted to the RN, and the RN transmits the data to the UE; and in the uplink, it is just on the opposite, which will no longer be described in details here.
In order to configure the resources of the backhaul link, it is to define the relay-physical dedicated downlink control channel (R-PDCCH), the relay-physical dedicated downlink shared channel (R-PDSCH) and the relay-physical dedicated uplink shared channel (R-PUSCH). The R-PDCCH can schedule the RN to receive the data on the R-PDSCH in one or more Un downlink subframes, and the R-PDCCH can schedule the RN to receive the data on the R-PUSCH in one or more Un uplink subframes.
The base station schedules the RN to transmit/receive the date in a plurality of Un uplink subframes through the R-PDCCH, thus saving the signaling expense of the R-PDCCH. In the case that the service volume of the UE of the macro cell increases, the base station can use this part of saved resources to schedule the transmission of the UE of the macro cell.
In the current scheduling technology, when transmitting in a plurality of subframes, the UE adopts the two kinds of scheduling ways, i.e. the above-mentioned semi-persistent scheduling and the above-mentioned TTI bundling, to perform the scheduling, but these two kinds of scheduling ways used by the UE when transmitting in a plurality of subframes are not suitable for scheduling the network element in the wireless relay system.
Taking the network element in the wireless relay system as an example, since the data of the RN is integrated with the data of one or more UEs of the relay cell, the data packet is relatively large, and the time interval is unfixed, while the semi-persistent scheduling way aims at the service of which the data packet is minor and the transmission time interval is relatively fixed, thus the RN does not possess the characteristic of the service applied for the semi-persistent scheduling, so the current above-mentioned semi-persistent scheduling is not suitable for scheduling the RN. In addition, the signal channel quality of the backhaul link is relatively good, so the retransmission probability of the RN is relatively low, and the TTI bundling way aims at a user at the border of the cell, of which the transmission success rate is low and the retransmission probability is high, and uplink subframe resource of the Un is limited, thus, if adopting the TTI bundling way, the uplink resource of the Un will be wasted, so the current above-mentioned TTI bundling is not suitable for scheduling the RN either.
In a word, the current ways of both the semi-persistent scheduling and the TTI bundling are not suitable for scheduling the RN, that is to say, after introducing the radio relay technology, the current scheduling way is still adopted to perform the scheduling, the scheduling for various network elements, such as, the UE, the RN, etc. can not be achieved compatibly. Now one scheduling solution which can be suitable for scheduling all kinds of the network elements commonly is needed urgently.